Production method for magnetic wire



1966 SHINTARO OSHIMA ET AL 3,279,959

PRODUCTION METHOD FOR MAGNETIC WIRE Filed June 2, 1964 United States Patent 3,279,959 PRODUCTION METHOD FOR MAGNETIC WIRE Shintaro Oshima, Musashino-shi, and Tetsusaburo Kamibayashi, Saitama-ken, Japan, assignors to Kokusai Denshin Denwa Kabushiki Kaisha, Tokyo-to, Japan, a joint-stock company of Japan Filed June 2, 1964, Ser. No. 371,955 Claims priority, application Japan, June 5, 1963, 38/28,606 7 Claims. (Cl. 148103) This invention relates to production methods for magnetic wires, more particularly to a new production method for conductive wire with ferromagnetic film deposited thereon.

Wire parametrons and wire memories in which the above mentioned memory wire is used have been recently developed. Such a wire parametron element is formed into abridge circuit including four arms of said magnetic wire, and such a wire memory is composed of said memory wires and conductive wires mutually arranged in an intersecting condition, whereby binary information is stored in or read out from the wire memory by energizing these wires. Accordingly, such a memory wire becomes an important material. A memory wire is generally produced by electrically or evaporatively depositing a ferromagnetic film on a conductive wire. These production methods, however, are generally accompanied by low production speed and other disadvantages, such as the necessity of maintaining rigid conditions in each production process.

An object of the preset invention is to provide a production method for memory wires suitable for use in electronic devices, such as wire parametrons and wire memories.

Another object of the invention is to provide a production method affording the manufacture of such magnetic wires by simple and economic production processes and with considerably high production speed.

According to the present invention there is provided a production method for conductive wire with ferromagnetic film deposited thereon (magnetic wire), comprising a process for causing a ferromagnetic material to surround in a firm manner an elongated non-magnetic conductive substance, a process for drawing, through dies, said elongated conductive substance surrounded with said ferromagnetic material, thereby obtaining a magnetic wire comprising a conductive substance wire coated with ferromagnetic film, and a process for heating in a short time the magnetic wire under a magnetic field applied along the surface of said magnetic wire, whereby the easy axis of the magnetic wire is established in the direction of the magnetic field.

The manner in which the aforestated objects as well as other objects and advantages may best be achieved will be understood more fully from a consideration of the following description of the principle and embodiments of the preset invention, taken in connection with the accompanying drawings, in which the same or equivalent parts are designated by the same reference characters, and in which:

FIG. 1 is a perspective view of a product in a process of this invention;

FIG. 2 is a fragmental, perspective view of a product in a process of this invention; and

FIGS. 3 and 4 are general views of devices for carrying out respective processes of this invention.

3,279,959 Patented Oct. 18, 1966 In the first process of the production method according to the present invention, a ferromagnetic material 2 is firmly deposited to surround an elongated non-magnetic conductive substance 1 as shown in FIG. 1, The conductive substance 1 is elongated, by means of a mould technique and/or a press technique. The material of the conductive substance 1 is a non-magnetic material, such as copper. Particularly, spring materials such as beryllium copper and Phosphor bronze are suitable because with the use of these spring materials the undesirable magnetostriction effect of a ferromagnetic material to be deposited thereon in case of composition or use of magnetic wire devices can be avoided.

The ferromagnetic material 2, such as permalloy having suitable composition for minimum magnetostriction effect, is previously formed into a tubular shape the inner diameter of which is slightly smaller than the diameter of the conductive substance 1. Since the inner diameter of the tube shaped material 2 becomes larger when the material 2 is heated at an appropriate temperature, for instance, 800 to 1000 degrees centigrade, the conductive substance I kept at a room temperature can be inserted in said heated material 2. In the other words, this process is a shrinkage fit. Accordingly, when the temperature of the material 2 decreases to room temperature, the ferroma netic material 2 is firmly fixed on the conductive substance 1 as is shown in FIG. 1.

The conductive substance 1 with the ferromagnetic material (hereinafter referred to as the product Wa) as shown in FIG. 1 is then extended into an elongated wire Wb as shown in FIG. 2 by means of dies. In this process, the outer layer of the product Wb may be shaved off to obtain a smooth surface of the product Wb. If rotating dies are employed in this process, a product Wb having a considerably smooth surface is obtained.

Another method for firmly placing the material 2 around the conductive substance 1 is to electrically deposit a ferromagnetic layer on the conductive wire 1 as shown in FIG. 2. In the case of deposition of permalloy material, said electrical deposition is carried out in an electrolyte in which the main components thereof are as follows: nickel sulfate (NiSO -6H O), nickel chloride (NiCl 6H O) and ferrous sulfate (FeSO -7H O). The compositional quantities of said components are selected so as to obtain minimum magnetostriction condition of the permalloy to be deposited. Boric acid (H BO a small quantity of saccharin (C H SO and a small quantity of lauri-c acid natrium (CH (CH OSO Na) can be employed as additional components of the electrolyte for carrying out uniform deposition and for reducing the magnitude of the coercive force of the ferromagnetic material 2. The current for electrical deposition is approximately 10 to 40 amperes square de-cimeter, with an electrolyte temperature of 50 degrees centigrade.

The material 2 can be deposited on the conductive substance 1 by the evaporative deposition technique or sputtering.

In the above-mentioned deposition process of the ferromagnetic material 2 on the conductive substance 1, the ratio of the diameter of the substance 1 to the thickness of the ferromagnetic material 2 can be generally selected to be the same as that in the desired completed magnetic wire. In the case of deposition by said heat treatment, however, the ratio is a little larger than the ratio of a completed magnetic wire because the surface layer is slightly removed so as to obtain a uniform film of the material 2 in the succeeding production process.

The conductive substance 1 with the material (herein referred as the product Wb) produced in the deposition process as mentioned above is then drawn, through a plurality of dies, into a magnetic wire (the product We) in the drawing process. FIG. 3 shows one example of a wire drawing device. The product is successively passed through dies 3a, 3b, 3c and 3i by being guided by guide rollers 4a, 4b, 3c, 4i and guide rollers 5a, 5b, 5c, 51. A shaft 6 supporting the rollers 4a, 4b, 4c,

and di is rotated at the same rotational speed as that of a shaft 7 supporting the rollers 5a, 5b, 5c, 5i. A casing 8 is employed for accommodating a lubricating liquid 9, such as a mixture of a vegetable oil and soap water. References 10 and 11 designate rollers and/or rotating dies. A tensioner 12 draws the magnetic wire (product Wc), and then a winding bobbin 13 receives the product Wc thereon. In this device, the center holes of the dies 3a, 3b, 3c, and Si are decreased step by step, whereby the diameter of product Wb is progressively decreased with every pass thereof into the dies 3a, 3b, 3c, and 3i. The reduction rate with respect to the diameter of the just preceding die (for example 3a) and the diameter of the just succeeding die (for example 3b) is selected at a value approximately equal to twenty percent (20%) or less. Said center holes of the dies are formed with hard edges such as diamond, tungsten, or steel. In order to compensate for every extension in length of the product Wb at every die and the maintain forces for pulling the product Wb in a stable condition, the diameters of the rollers are successively increased. Said lubricating liquid 9 has the effect of producing a smooth surface of the product Wc. This drawing process produces the product We which is a conductive wire with a coat ferromagnetic film, the diameter of the product We being an optional, usable value, such as approximately 0.05 to 2.0 millimeters. Moreover, the thickness of the film can be made thinner than 10 microns.

The easy axis of the ferromagnetic film of the product Wc is normally established in the longitudinal direction of the product Wc. When a more uniform characteristic of the easy axis is desirable, a heat treatment is carried out with respect to the product Wc.

The heating process of this invention is carried out in a very short necessary time in a magnetic field applied along the surface of said magnetic wire Wc. FIG. 4(A) shows a coil heater 14, such as tungsten wire or nickelchromium wire, for heating the magnetic wire Wc passing therethrough and for applying a longitudinal magnetic field to the magnetic wire Wc. A power source 15 supplies a direct current or an alternating current to the coil heater 14. A pipe heater 16 composed of, for example, stainless steel, as shown in FIG. 4 is employed only for heating the magnetic wire Wc passing therethrough by means of a current supplied from a current source 15. The magnetic field in this case, however, is applied by a direct current or an alternating current flowing through the magnetic wire Wc. The heating process of this invention is carried out at a traveling speed of approximately 1.5 centimeter/second at a heater temperature of approximately 500 to 700 degrees centigrade. This heating process'is carried out in a reduction gas mixture, such as a mixture of isopropyl alcohol and nitrogen, to prevent oxidation of the surface of the magnetic wire. The temperature of the heated magnetic wire Wc reaches a normal condition in atmospheric air. This heating process can also correct the winding set or undesirable stress in the magnetic wire Wc.

If necessary, a thin insulation layer is coated on the magnetic wire Wc by the use of a baking technique.

As mentioned above in detail, the magnetic wire according to this invention can be produced easily and at a high production speed. Moreover, the wire has a uniform easy axis established in a predetermined direction, and the magnetic wire production method of this invention is suitable for mass-production of such magnetic wire to be used in electronic devices.

While particular embodiments of this invention have been described and shown, it will, of course, be understood that it is not to be limited thereto, since many modifications may be made of this invention, and therefore, it is contemplated by the appended claims to cover all such modifications as fall within the true spirit and Scope of this invention.

What we claim is:

1. A production method for a conductive wire with ferromagnetic film deposited thereon, comprising a process for placing a ferromagnetic material firmly around an elongated non-magnetic conductive substance, a process for drawing, through dies, said elongated conductive substance surrounded by said ferromagnetic material thereby obtaining a magnetic wire comprising a conductive substance wire with a ferromagnetic film deposited thereon, and a process for heating the magnetic wire under a magnetic field applied along the surface of said magnetic wire, whereby the easy axis of the magnetic wire is established in the direction of the magnetic field.

2. A production method for a conductive wire with ferromagnetic film deposited thereon, comprising a process for firmly fitting a tube shaped ferromagnetic material on a nonmagnetic elongated conductive substance by use of the shrinkage fit technique, a process for drawing, through dies, said elongated conductive substance surrounded with said ferromagnetic material, thereby obtaining a magnetic wire comprising a conductive wire with a ferromagnetic film deposited thereon, and a process for heating the magnetic wire under a magnetic field applied along the surf-ace of said magnetic wire, whereby the easy axis of the magnetic wire is established in the direction of the magnetic field.

3. A production method for a conductive wire with ferromagnetic film deposited thereon, comprising a process for electrically depositing a ferromagnetic material layer on a non-magnetic, elongated conductive substance, a process for drawing, through dies, said elongated conductive substance surrounded with said ferromagnetic material, thereby obtaining a magnetic wire comprising a conductive substance wire with a ferromagnetic film deposited thereon, and a process for heating the magnetic wire under a magnetic field applied along the surface of said magnetic wire, whereby the easy axis of the magnetic wire is established in the direction of the magnetic field.

4. A production method for a conductive wire with ferromagnetic film deposited thereon, comprising a process for placing a ferromagnetic material firmly around an elongated non-magnetic conductive substance, a process for drawing, through dies, said elongated conductive substance surrounded with said ferromagnetic material, thereby obtaining a magnetic wire comprising a conductive substance wire with a ferromagnetic film deposited thereon, and a process for heating the magnetic wire under a magnetic field applied in the longitudinal direction of the wire, whereby the easy axis of the magnetic wire is established in the direction of the magnetic field.

5. A method as claimed in claim 4, wherein said magnetic field is applied by means of a coil with a current flowing therethrough, the wire being caused to travel through the central axial space of the coil.

6. A production method for a conductive wire with ferromagnetic film deposited thereon, comprising a process for placing a ferromagnetic material firmly around an elongated non-magnetic conductive substance, a process for drawing, through dies, said elongated conductive substance surrounded with said ferromagnetic material, there- 5 6 by obtaining a magnetic Wire comprising a conductive sub- References Cited by the Examiner stance Wire With a ferromagnetic film deposited thereon, UNITED STATES PATENTS and a process 101' heating the magnetic wire under a magnetic field applied in the circumferential direction of the 2105426 1/1938 McManus 2,443,636 6/1948 Nesbltt 148-121 Wire, whereby the easy axis of the magnetic wire is estab- 5 lished in the direction of the magnetic field. 3039891 6/1962 Mltcheu 148 103 7. A method as claimed in claim 6, wherein said m'agnetic field is applied by passing an appropriate current DAVID RECK P'lmary Examiner through the conductive Wire. N. F. MARKVA, Assistant Examiner. 

1. A PRODUCTION METHOD FOR A CONDUCTIVE WIRE WITH FERROMAGNETIC FILM DEPOSITED THEREON, COMPRISING A PROCESS FOR PLACING A FERROMAGNETIC MATERIAL FIRMLY AROUND AN ELONGATED NON-MAGNETIC CONDUCTIVE SUBSTANCE, A PROCESS FOR DRAWING, THROUGH DIES, SAID ELONGATED CONDUCTIVE SUBSTANCE SURROUNDED BY SAID FERROMAGNETIC MATERIAL THEREBY OBTAINING A MAGNETIC WIRE COMPRISING A CONDUCTIVE SUBSTANCE WIRE WITH A FERROMAGNETIC FILM DEPOSITED THEREON, ANDA PROCESS FOR HEATING THE MAGNETIC WIRE UNDER A MAGNETIC FIELD APPLIED ALONG THE SURFACE OF SAID MAGNETIC WIRE, WHEREBY THE EASY AXIS OF THE MAGNETIC WIRE IS ESTABLISHED IN THE DIRECTION OF THE MAGNETIC FIELD. 